Most people buy 2nd hand Metering Heads, but they are all 20 odd years old now, so good ones are few and far between. It's a case of trial and error. If he is prepared to take the chance on it, they can be bought for around £50-£100 second hand, but he may have to buy a few before he gets a good one.

Generally best to get one from a car that was known to be be running OK, but not where the Metering Head has been sitting in someones shed for 3 years.